This invention relates generally to waste disposal and more particularly to an improved system for sterilizing infectious waste.
As is known in the art, waste disposal is an issue of growing public concern. Increasing quantities of waste are causing landfills to reach maximum capacity sooner than anticipated. As a result, municipalities are being forced to transport waste to remote processing facilities at considerable cost.
As is also known in the art, the disposal of infectious, or pathogenic waste presents a variety of concerns. In particular, the AIDS epidemic has heightened awareness of the risks involved with handling pathogenic waste materials. Additionally, recent incidents of medical waste appearing along coastal waterways has prompted government regulations regarding the disposal of medical refuse.
Various techniques are currently utilized for the disposal of infectious waste material. The most common method for processing infectious waste is incineration. A hospital may have an incinerator located at the facility or, alternatively, may transport its waste to an incinerator at an off-site location. Shipping the waste to an off-site incinerator is, generally, less expensive since the cost of the incinerator, as well as its maintenance is avoided. On the other hand, having an incinerator located at the hospital may reduce the risk of infection to the individuals who transport the refuse due to the fact that the waste is carried a shorter distance. However, while the risk of infection to the waste handler is reduced as the distance that the waste is transported is reduced, the risk still exists when any transport of infectious material is required. For example, the individual carrying a bag of contaminated material may inadvertently hit the bag against a wall or drop the container causing it to tear and waste to leak out. Also, sharp objects, such as hypodermic syringes or broken glass from items used for cultures or tissue specimens, may puncture the bag as well as the individual transporting it.
An equally serious concern regarding the use of incinerators is that certain materials yield ash which may contain carcinogenic or other hazardous materials. Relatively costly precautions are generally required to ensure that the emissions are non-toxic. Furthermore, the certification required to operate an incinerator may be difficult to obtain.
More recently, microwave energy has been investigated as an alternative means for sterilizing contaminated waste. Microwave energy may be used to heat the medical waste to a suitable disinfecting temperature or, alternatively, to a temperature which will incinerate the waste. However, the cost of microwave energy generally exceeds that of conventional energy sources and, thus, microwave energy may be an unnecessarily expensive alternative.
Alternatively, infectious waste may be processed in an autoclave in which sterilization results from exposure to steam. Generally, this technique is utilized with re-usable instruments and containers. While autoclaving may be suitable to render infectious materials sterile for re-use, non-sterilized items can be easily mistaken for ones which have been processed in the autoclave. Thus, a serious risk of exposure to infected re-usable materials exists.
Autoclaving may also be used to disinfect disposable items prior to depositing such items in a landfill. However, as a result of the growing public concern regarding pathogenic waste, an emerging requirement has been that the waste not only be rendered harmless but also unrecognizable as medical refuse prior to being deposited in a landfill. Since, during autoclaving the medical containers and instruments are left intact after being disinfected, autoclaving does not render the medical waste unrecognizable as such.
As is also known in the art, another method of infectious waste disposal includes autoclaving in conjunction with exposure to air heated to temperatures high enough to melt the plastic waste. This method is suitable since today, medical instruments and containers are predominantly made of plastic. An example of this type of waste disposal unit is described in U.S. Pat. No. 3,958,936. In this unit, air is heated to a temperature of at least 450.degree. F. and is directed to a melting chamber in which the infectious waste is disposed. The heated air melts the plastic waste material to a flowable state. An afterburner exhaust arrangement is used to incinerate the vapors evolved during the melting process. When the heating and melting cycle is completed, the chamber is allowed to cool. Upon cooling, the melted material solidifies into a block which can be easily removed and disposed of. Thus, this arrangement renders the pathogenic material harmless and unrecognizable as medical waste. Also, generally, items such as needles and surgical blades will become embedded in the resulting solid block thereby reducing the likelihood of such needles injuring the waste handler. Additionally, the volume of the waste is reduced by the melting process.